June 1994 LM2941 LM2941C 1A Low Dropout Adjustable Regulator General Description The LM2941 positive voltage regulator features the ability to source 1A of output current with a typical dropout voltage of 0 5V and a maximum of 1V over the entire temperature range Furthermore a quiescent current reduction circuit has been included which reduces the ground pin current when the differential between the input voltage and the output voltage exceeds approximately 3V The quiescent current with 1A of output current and an input-output differential of 5V is therefore only 30 ma Higher quiescent currents only exist when the regulator is in the dropout mode (V IN b V OUT s 3V) Designed also for vehicular applications the LM2941 and all regulated circuitry are protected from reverse battery installations or two-battery jumps During line transients such as load dump when the input voltage can momentarily exceed the specified maximum operating voltage the regulator will automatically shut down to protect both the internal circuits and the load Familiar regulator features such as short circuit and thermal overload protection are also provided Features Connection Diagram and Ordering Information 4-Lead TO-3 (K) TL H 8823 7 Bottom View Order Number LM2941K 883 See NS Package Number K04A Output voltage adjustable from 5V to 20V Dropout voltage typically 0 5V e 1A Output current in excess of 1A Trimmed reference voltage Reverse battery protection Internal short circuit current limit Mirror image insertion protection P a Product Enhancement tested TTL CMOS compatible switch (TO-220) Plastic Package TL H 8823 2 Front View Order Number LM2941T or LM2941CT See NS Package Number TO5A LM2941 LM2941C 1A Low Dropout Adjustable Regulator (TO-263) 5-Lead Surface-Mount Package TL H 8823 8 TL H 8823 9 Order Number LM2941S or LM2941CS See NS Package Number TS5B C1995 National Semiconductor Corporation TL H 8823 RRD-B30M75 Printed in U S A
Absolute Maximum Ratings (Note 1) If Military Aerospace specified devices are required please contact the National Semiconductor Sales Office Distributors for availability and specifications Input Voltage (Survival Voltage s 100 ms) LM2941K LM2941T LM2941S 60V LM2941CT LM2941CS 45V Internal Power Dissipation (Note 3) Internally Limited Maximum Junction Temperature 150 C Storage Temperature Range b65 C s T J s a150 C Lead Temperature (Soldering 10 seconds) TO-3 (K) Package TO-220 (T) Package TO-263 (S) Package ESD susceptibility to be determined Operating Ratings Maximum Input Voltage Temperature Range LM2941K LM2941T LM2941CT LM2941S LM2941CS 300 C 260 C 260 C 26V b55 C s T J s 150 C b40 C s T J s 125 C b0 C s T J s 125 C b40 C s T J s 125 C b0 C s T J s 125 C Electrical Characteristics LM2941K LM2941T LM2941S 5V s V O s 20V V IN e V O a 5V C O e 22 mf unless otherwise specified Specifications in standard typeface apply for T J e 25 C while those in boldface type apply over the full Operating Temperature Range LM2941K Parameter Conditions Typ Limit (Notes 2 4) Reference Voltage 5 ma s (Note 6) 1 275 LM2941T LM2941S Limit (Note 5) Units (Limits) 1 237 1 211 1 237 1 211 V(min) 1 313 1 339 1 313 1 339 V(max) Line Regulation V O a 2V s V IN s 26V e 5 ma 4 10 10 10 10 mv V(max) Load Regulation 50 ma s 7 10 10 10 10 mv V(max) Output Impedance 100 madc and 20 marms f O e 120 Hz 7 mx V Quiescent Current V O a 2V s V IN k 26V e 5 ma 10 15 20 15 20 ma(max) RMS Output Noise %ofv OUT V IN e V O a 5V e 1A 30 45 60 45 60 ma(max) 10 Hz 100 khz e 5mA 0 003 % Ripple Rejection f O e 120 Hz 1 Vrms I L e 100 ma 0 005 0 02 0 04 0 02 0 04 % V(max) Long Term Stability 0 4 % 1000 Hr Dropout Voltage e 1A 0 5 0 8 1 0 0 8 1 0 V(max) e 100 ma 110 200 200 200 200 mv(max) Short Circuit Current V IN max e 26V (Note 7) 1 9 1 6 1 3 1 6 A(min) Maximum Line V O max 1V above nominal V O 75 60 60 60 60 V(min) Transient R O e 100X Ts100 ms Maximum Operational Input Voltage Reverse Polarity DC Input Voltage Reverse Polarity Transient Input Voltage R O e 100X V O tb0 6V T s 100 ms R O e 100X 31 26 26 26 26 V DC b30 b15 b15 b15 b15 V(min) b75 b50 b50 b50 b50 V(min) Threshold Voltage 1 30 0 80 0 80 0 80 0 80 V(max) ON Threshold Voltage 1 30 2 00 2 00 2 00 2 00 V(min) OFF Threshold Current V e 2 0V 50 100 300 100 300 ma(max) 2
Electrical Characteristics LM2941CT LM2941CS 5V s V O s 20V V IN e V O a 5V C O e 22 mf unless otherwise specified Specifications in standard typeface apply for T J e 25 C while those in boldface type apply over the full Operating Temperature Range Parameter Conditions Typ Reference Voltage 5 ma s (Note 6) 1 275 Limit (Note 5) 1 237 1 211 1 313 1 339 Units (Limits) V(min) V(max) Line Regulation V O a 2V s V IN s 26V e 5 ma 4 10 mv V(max) Load Regulation 50 ma s 7 10 mv V(max) Output Impedance 100 madc and 20 marms f O e 120 Hz 7 mx V Quiescent Current V O a 2V s V IN k 26V e 5 ma 10 15 ma(max) RMS Output Noise %ofv OUT V IN e V O a 5V e 1A 30 45 60 ma(max) 10 Hz 100 khz e 5mA 0 003 % Ripple Rejection f O e 120 Hz 1 Vrms I L e 100 ma 0 005 0 02 % V(max) Long Term Stability 0 4 % 1000 Hr Dropout Voltage e 1A 0 5 0 8 1 0 V(max) e 100 ma 110 200 200 mv(max) Short Circuit Current V IN max e 26V (Note 7) 1 9 1 6 A(min) Maximum Line V O max 1V above nominal V O 55 45 V(min) Transient R O e 100X Ts100 ms Maximum Operational Input Voltage Reverse Polarity DC Input Voltage Reverse Polarity Transient Input Voltage R O e 100X V O tb0 6V T s 100 ms R O e 100X 31 26 V DC b30 b15 V(min) b55 b45 V(min) Threshold Voltage 1 30 0 80 V(max) ON Threshold Voltage 1 30 2 00 V(min) OFF V e 2 0V Threshold Current 50 100 ma(max) Note 1 Absolute Maximum Ratings indicate limits beyond which damage to the device may occur Operating ratings indicate conditions for which the device is intended to be functional but device parameter specifications may not be guaranteed under these conditions For guaranteed specifications and test conditions see the Electrical Characteristics Note 2 A military RETS specification available upon request At the time of printing the LM2941 883 RETS specification complied with the boldface limits in this column The LM2941K 883 may also be procured to a Standard Military Drawing Note 3 The maximum power dissipation is a function of T J (max) i JA and T A The maximum allowable power dissipation at any ambient temperature is P D e (T J (max) b T A ) i JA If this dissipation is exceeded the die temperature will rise above 150 C and the LM2941 will go into thermal shutdown For the LM2941T and LM2941CT the junction-to-ambient thermal resistance (i JA )is53 C W and the junction-to-case thermal resistance (i JC )is3 C W For the LM2941K i JA is 35 C W and i JC is 4 C W The junction-to-ambient thermal resistance of the TO-263 is 73 C W and junction-to-case thermal resistance i JC is 3 C If the TO-263 package is used the thermal resistance can be reduced by increasing the P C board copper area thermally connected to the package Using 0 5 square inches of copper area i JA is 50 C W with 1 square inch of copper area i JA is 37 C W and with 1 6 or more square inches of copper area i JA is 32 C W Note 4 All limits guaranteed at room temperature (standard typeface) and at temperature extremes (boldface type) All limits are used to calculate Outgoing Quality Level and are 100% production tested Note 5 All limits guaranteed at room temperature (standard typeface) and at temperature extremes (boldface type) All room temperature limits are 100% production tested All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods Note 6 The output voltage range is 5V to 20V and is determined by the two external resistors R1 and R2 See Typical Application Circuit Note 7 Output current capability will decrease with increasing temperature but will not go below 1A at the maximum specified temperatures 3
Typical Performance Characteristics Dropout Voltage Dropout Voltage vs Temperature Output Voltage Quiescent Current vs Temperature Quiescent Current Quiescent Current Line Transient Response Load Transient Response Ripple Rejection Output Impedance TL H 8823 4 4
Typical Performance Characteristics (Continued) Low Voltage Behavior Low Voltage Behavior Output Capacitor ESR Output at Voltage Extremes Output at Voltage Extremes Peak Output Current TL H 8823 5 Maximum Power Dissipation (TO-220) Maximum Power Dissipation (TO-3) Maximum Power Dissipation (TO-263) (Note 3) TL H 8823 10 5
Definition of Terms Dropout Voltage The input-voltage differential at which the circuit ceases to regulate against further reduction in input voltage Measured when the output voltage has dropped 100 mv from the nominal value obtained at (V OUT a 5V) input dropout voltage is dependent upon load current and junction temperature Input Voltage The DC voltage applied to the input terminals with respect to ground Input-Output Differential The voltage difference between the unregulated input voltage and the regulated output voltage for which the regulator will operate Line Regulation The change in output voltage for a change in the input voltage The measurement is made under conditions of low dissipation or by using pulse techniques such that the average chip temperature is not significantly affected Load Regulation The change in output voltage for a change in load current at constant chip temperature Long Term Stability Output voltage stability under accelerated life-test conditions after 1000 hours with maximum rated voltage and junction temperature Output Noise Voltage The rms AC voltage at the output with constant load and no input ripple measured over a specified frequency range Quiescent Current That part of the positive input current that does not contribute to the positive load current The regulator ground lead current Ripple Rejection The ratio of the peak-to-peak input ripple voltage to the peak-to-peak output ripple voltage Temperature Stability of V O The percentage change in output voltage for a thermal variation from room temperature to either temperature extreme Typical Applications 5V to 20V Adjustable Regulator V OUT e Reference voltage c R1 a R2 where V REF e 1 275 typical R1 Solving for R2 R2 e R1 V O V REF b 1 J Note Using 1k for R1 will ensure that the input bias current error of the adjust pin will be negligible Do not bypass R1 or R2 This will lead to instabilities TL H 8823 3 Required if regulator is located far from power supply filter C OUT must be at least 22 mf to maintain stability May be increased without bound to maintain regulation during transients Locate as close as possible to the regulator This capacitor must be rated over the same operating temperature range as the regulator and the ESR is critical see curve 1A Switch TL H 8823 6 To assure shutdown select Resistor R3 to guarantee at least 300 ma of pull-up current when S1 is open (Assume 2V at the pin ) 6
Equivalent Schematic Diagram TL H 8823 1 7
8
Physical Dimensions inches (millimeters) Order Number LM2941K 883 NS Package Number K04A Order Number LM2941T or LM2941CT NS Package Number T05A 9
LM2941 LM2941C 1A Low Dropout Adjustable Regulator Physical Dimensions inches (millimeters) (Continued) TO-263 5-Lead Plastic Surface Mount Package Order Number LM2941S or LM2941CS NS Package Number TS5B Lit 108022 LIFE SUPPORT POLIC NATIONAL S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION As used herein 1 Life support devices or systems are devices or 2 A critical component is any component of a life systems which (a) are intended for surgical implant support device or system whose failure to perform can into the body or (b) support or sustain life and whose be reasonably expected to cause the failure of the life failure to perform when properly used in accordance support device or system or to affect its safety or with instructions for use provided in the labeling can effectiveness be reasonably expected to result in a significant injury to the user National Semiconductor National Semiconductor National Semiconductor National Semiconductor National Semiconductores National Semiconductor Corporation GmbH Japan Ltd Hong Kong Ltd Do Brazil Ltda (Australia) Pty Ltd 2900 Semiconductor Drive Livry-Gargan-Str 10 Sumitomo Chemical 13th Floor Straight Block Rue Deputado Lacorda Franco Building 16 P O Box 58090 D-82256 F4urstenfeldbruck Engineering Center Ocean Centre 5 Canton Rd 120-3A Business Park Drive Santa Clara CA 95052-8090 Germany Bldg 7F Tsimshatsui Kowloon Sao Paulo-SP Monash Business Park Tel 1(800) 272-9959 Tel (81-41) 35-0 1-7-1 Nakase Mihama-Ku Hong Kong Brazil 05418-000 Nottinghill Melbourne TWX (910) 339-9240 Telex 527649 Chiba-City Tel (852) 2737-1600 Tel (55-11) 212-5066 Victoria 3168 Australia Fax (81-41) 35-1 Ciba Prefecture 261 Fax (852) 2736-9960 Telex 391-1131931 NSBR BR Tel (3) 558-9999 Tel (043) 299-2300 Fax (55-11) 212-1181 Fax (3) 558-9998 Fax (043) 299-2500 National does not assume any responsibility for use of any circuitry described no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications
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